1. Field of the Invention
This invention relates to an extrudable fluorosilicone sealant having an in situ treated filler, said sealant curing upon exposure to moisture to an improved tensile strength elastomer.
2. Background Information
Fluorosilicone sealants which cure upon exposure to moisture are currently available, but they are lacking in sufficient tensile strength for some applications. Fluorosilicone elastomers having higher tensile strengths are available, but they are high consistency materials which must be molded under pressure.
Smith teaches in U.S. Pat. No. 3,635,743, issued Jan. 18, 1972, an improved reinforcing silica filler made by first treating a reinforcing silica filler with ammonia and then treating the filler with hexamethyldisilazane.
Jeram teaches a solvent resistant room temperature vulcanizable silicone rubber composition in U.S. Pat. No. 4,029,629, issued June 14, 1977, which comprises a blend of vinyl-terminated polysiloxanes having from 2 to 98 mole percent of alkylperfluoroalkylalkylene siloxy units in the polymer chain, a hydride cross-linking agent, and platinum catalyst.
Lee and Maxson teach in U.S. Pat. No. 4,711,928, issued Dec. 8, 1987, a process for producing a moisture curing sealant cured through use of a titanium catalyst. The sealant is made with a process which generates an in situ treated reinforcing filler through the use of a disilazane treating agent. The vinyl endblocked polymer used is converted into a polymer with alkoxysilethylene endblocking during the process to give the final sealant improved shelf life.